In a smart battery design, an electronic supply voltage control circuit is integrated in the battery structure. Such an electronic circuit may include an end-of-life detector (EOL), an oscillator stage, a power control unit, or a communication interface. The electronic circuit also includes a DC-DC converter between the external positive terminal and the internal positive terminal. This DC-DC converter is powered on continuously or when the supply voltage is close or equal to an end-of-battery life threshold (EOL). This may be a Boost converter or a Buck converter. This makes it possible to extend battery life while supplying a sufficient supply voltage above a minimum limit. The battery may also be of the rechargeable type.
As mentioned above, reference may be made to U.S. Pat. No. 6,198,250 B1 which discloses a smart battery or cell of this type, which includes a controller circuit. The controller circuit is connected to the cell or battery supply terminals. The controller circuit makes it possible to extend battery life. To achieve this, the controller circuit includes a DC-DC converter clocked by an oscillator to convert the battery or cell voltage into an output voltage, which may be higher than a cutoff voltage or an end-of-battery-life voltage. The converter may be started as soon as the battery voltage reaches an end-of-battery-life voltage threshold in order to extend battery life.
According to FIG. 5B of U.S. Pat. No. 6,198,250 B1, the controller circuit is connected in a central position to the back cover of the battery, which forms the negative terminal of the battery, and to one of the electrochemical substances defining a negative pole. The controller circuit is connected by an input terminal to one of the electrochemical substances defining an internal positive pole by means of an electrical connecting tab. The controller circuit is connected by an output terminal to a wall defining an external positive battery terminal by means of another electrical connecting tab. An insulator must also be provided between the controller circuit and the electrochemical substances. The controller circuit arrangement occupies a relatively large space in the battery structure, which constitutes a drawback. Such an arrangement of the controller circuit does not easily allow it to be arranged in a battery of smaller dimensions, that is to say in a battery of smaller dimensions than an AAA battery.